The present invention relates to a respirator mask and specifically to a respirator mask with includes replaceable cartridges.
In the prior art respirator masks have been made with replaceable cartridges. These respirator masks normally include cartridges being replaceable by either a screw on joint, using threaded connections or using a bayonet type joint between the cartridge and the mask. In these prior art devices it is often difficult to replace the cartridge since the threads may misalign or the bayonet joint may be difficult to engage. In addition in the prior art, if the cartridge is not either threaded on properly or connected properly using the bayonet joint, the mask may allow for the leakage of outside, unfiltered air into the mask. It is sometimes difficult to tell if the cartridge has been properly seated into a mask, which as indicated above, can allow for a dangerous situation of the mask allowing in unfiltered air.
The prior art masks are also relatively expensive to manufacture since the threaded connections must be accurately dimensioned and the bayonet joint must also be accurately dimensioned to ensure a proper seal.
In order to overcome the deficiencies of the prior art respirator masks as indicated above, a prior invention, now the subject of U.S. Pat. No. 5,505,197 and assigned to the same assignee as the instant invention, provided for a respirator mask which uses replaceable cartridges, but does not incorporate any threaded connection or a bayonet joint to have the cartridge attached to the mask. Specifically, in U.S. Pat. No. 5,505,197 the cartridge is attached to the mask using a simple groove around an interior inner end of the cartridge which mates with a complementary opening having a flange portion which is received in the groove inner end of the cartridge.
In the prior invention the mask body is made of a resilient, flexible rubber-like material and the flange portion around the opening itself acts as a joint member in cooperation with the groove to have the cartridge simply attached to the mask using this combination flange/groove construction. Since the mask is made of a flexible resilient material, the flange provides for an airtight seal between the cartridge and the mask.
Because of the specific groove and flange structure and the resiliency of the mask body itself, it is simple to install a cartridge by inserting the cartridge on an angle to engage the flange in one portion of the groove and then by merely stretching the resilient mask body around the opening the remaining groove portion seats into place to produce the proper sealing of the cartridge to the mask.
The difficulty with this type of design is that the mask body, being made of the resilient flexible rubber-like material is quite heavy and it would be desirable to replace the mask body with a thin rigid member, which is strong but yet much lighter in weight.